Hypodermic syringe operating means



Nov. 3, 1964 J. w. HOLTER HYPODERMIC SYRINGE OPERATING MEANS Filed Jan. 10, 1962 INVENTOR. JOHN W. HOLTER BY ATTORNEY United States Patent Pennsylvania Filed Jan. 10, 1962, Ser. No. 165,368 3 Claims. (Cl. 128-2) This invention relates to hypodermic syringe operating means and use thereof and has particular reference to a means for elfecting slow and controlled injection of a liquid into the body, or similar injection of small quantities of liquid into chemical processes.

The objects of the invention may be best appreciated from consideration of a particular problem. For the radiological examination of the lymphatic system it is customary to inject into that system an X-ray opaque medium such as a suspension of barium sulphate or the like in poppyseed or other oil. Such a suspension is quite viscous, and it is customary to effect its injection into the lymph gland in an instep or back of the hand from which it will flow throughout the body. The lymphatic passages are very small, and the procedure takes a long time and constant attention because the injection may be only effected, by manual operation, by repeated injection of small amounts of the suspension at spaced intervals, the intervals being necessary to permit the slow flow to occur without the danger of build-up of excessive pressure. It will be obvious that the whole procedure must be very carefully controlled, and may well take a period upwards of many minutes to an hour or more. As heretofore carried out, the procedure was not even associated with any effective way of observing what occurred, and for purposes of safety, the intermittent injection had to be very small and excessive time and attention were required to insure proper distribution of the suspension.

It is the general object of the present invention to provide an apparatus for controlling the piston of a hypodermic syringe to provide automatic injection of a liquid in a situation such as that described without the necessity for constant vigilant attention. Furthermore, in accordance with the invention, the procedure is carried out automatically, there being provided a pressure-sensitive switching arrangement which insures continuance of operation Whenever the pressure is at a safe value.

Consistently with the desired operation provision is made for the rapid restoration of the apparatus to initial condition so thata hypodermic syringe may be removed and replaced.

The foregoing and other objects of the invention will become apparent from the following description, read in conjunction with the accompanying drawing, in which:

FIGURE 1 is a plan view of a preferred form of the apparatus shown partly in section to illustrate details of construction; and

FIGURE 2 is a transverse section taken on the plane indicated at 22 in FIGURE 1.

In a preferred embodiment of the invention, the apparatus comprises a base 2 provided with a bracket 4 and a housing 6 which contains certain of the elements and also serves as a support. An intermediate bracket 8 is also provided.

A fitting 14) carried by the housing 6 is provided with a coupling 12 in which the outlet of a hypodermic syringe 14 may be secured. This syringe includes the usual piston 16, the inner end of which is indicated at 18. The syringe is calibrated as indicated at 20 in suitable units for the particular operation desired.

The fitting is provided with a passage 22 communicating at one end with the opening in the coupling 12 and arranged to provide flow from the syringe to a tube 26 secured on a fitting 24, the end of the tube carrying in conventional fashion the hypodermic needle 27 to be inserted into the body for injection of the liquid from the syringe.

The passage 22 communicates with a branch passage 28 running to the interior of a bellows 30 which has a spring action so that its head 32 moves in proportion to the pressure therein.

A follower lever assembly 34 is engaged by the head 32 and is mounted on, and to operate, a microswitch 36 to open this switch as pressure increases. The microswitch 36 is carried by the stem 38 which is threaded into a suitable nut in the wall of the housing 6 and carries a knob 44 for manual manipulation, the knob 40 carrying an index pointer 42 movable adjacent to a calibrated scale on the face of the housing, the scale not being shown.

While still considering the right-hand assembly, reference may be made to the provision of a heating coil 44 surrounding the fitting it) which is metallic, the heater being connected to current supply terminals 46. The heater 44 is chosen to provide a sufiicient heat input to bring the walls of passage 22 near or slightly above body temperature so that the liquid injected will be approximately at body temperature. This result is achieved because the rate of flow through the passage 22 is quite slow and effective heat transfer to the liquid is accordingly achieved. This arrangement makes it unnecessary to attempt to maintain the syringe itself and its contents at the desired temperature.

The bracket 4 supports a motor 48 of the so-called instrument type which, as is conventional, is synchronous and embodies internal reduction gearing so as to provide a suitable slow drive of its output shaft. A variable speed motor may, of course, be used. In the case of a typical design for injecting a radiologically opaque medium into the lymphatic system, the output shaft of the motor may suitably rotate at a rate of about two revolutions per minute. As will be mentioned hereafter, it may sometimes be desirable to effect either faster or slower rates of injection, and this may be conveniently achieved merely by replacing the motor 48 by another motor having a suitable output shaft speed. The motor is connected in series with the switch 36 to the current supply terminals 46.

Secured to the motor shaft is a sleeve 50 which at its right-hand end, as shown, is provided with internal threads 52 so that it provides a rotating nut. The threaded end of the sleeve has a bearing in a member 54 carried by the bracket 8. Journalled in and slidable through an opening in the member 54 is a screw 56 engaging the threads 52. The screw 56 is provided with a disc head 58 arranged to engage the outer end of the piston 16 of the syringe.

This head is desirably knurled for rapid manual rotation as described hereafter.

The screw 56 has a flat side as indicated at 60 which is engageable by the flat face 66 of an elongated opening 64 in a slide 62 mounted for transverse movement in an opening in the member 54 and urged toward the left as viewed in FIGURE 2 by a strong spring 68 reacting between the member 54 and a manually operable button 70 carried by the slide. As will be evident from FIGURE 2, the arrangement is such as normally to prevent rotation of the screw 56, the screw being releasable by manual pressure exerted on the button 70.

In the use of the device described, the filled syringe 14 is secured to the fitting 10 and the tube and needle connections are made with the needle properly inserted into the body. With the motor deenergized (through a main switch, not shown) the button 70 may be pushed to free the screw 56 which may be then rapidly rotated through the knurled disc 58 to bring it in contact with the piston Patented Nov. 3, 1964 16 of the syringe. Release of the button then locks it against rotation while permitting, nevertheless, its slow drive. The operation may be started with energlzation of the motor to rotate the sleeve 50 which then produces axial movement of the non-rotating screw 56 and the syringe piston. So long as the pressure does not exceed a critical pressure established by adjustment of the knob 49, the switch 36 will remain closed and slow injection of the liquid will take place, the liquid in its passage through the fitting 10 being heated as previously described. Whenever, however, the pressure exceeds that predetermined by the knob setting, the expansion of the bellows 30 will open the switch 36 stopping the motor operation. This stoppage occurs substantially instantaneously because of the great reduction involved in the internal gearing of the motor. The liquid will then ordinarily spread through the body passages so that the pressure will drop and the switch arm 34 will be released sufficiently to close again the switch 36 to start the motor operation. The cycles of operation and stoppage just described will repeat to maintain a condition of injection which will not involve the occurrence of an excess pressure. It will be evident that the operation will ordinarily be greatly speeded up as compared with that resulting from manual operation of the syringe because of the fact that continuous response to pressure exists, rather than the necessity for an operator to permit a safe, and therefore unduly long period between increments of in jection. An attendant, or even the patient, need do no more than observe that the syringe is being operated intermittently without undue intervals of non-operation. For this observation it is desirable to provide a pilot light 72 in series or in parallel with the motor to indicate when the motor is or is not operating. stoppage of the motor over a long period may, of course, indicate clogging of some passages in the body, the needle, or the apparatus itself.

It may be here noted that desirably the screw 56 is of a length such as to run out of the thread 52 before the piston 16 engages the bottom of the cylinder in the syringe, thereby to safeguard against damage.

After the operation is completed, the pushbutton 70 may be manipulated to release the screw 56 which may be then rapidly spun to remove the head 58 from the syringe so that the syringe may be removed. The spinning of the screw will ordinarily be continued so as to clear the position which will be occupied by the end of the piston of a new or refilled syringe.

While the invention has heretofore been described as primarily used for injection into the lymphatic system, requiring quite slow rate of injection because of the very small passages involved, it will be evident that the apparatus may be used quite generally for injections of liquids into the body wherever such injections must be rather slowly effected and for safety may not exceed some rate which will cause undue pressure.

The apparatus is further useful where it is desired to effect injections remotely even though the rate of injection may be rather rapid. Such a situation exists when X-ray observation of the progress of an injection is necessary. In such cases the apparatus, closely adjacent to the patient and in the field of radiation, may operate without an attendant being close thereto to the extent of possibly receiving because of continuous activities a cumulative overdose of radiation.

it will be evident that various changes in details of the apparatus may be made without departing from the invention as defined in the following claims.

What is claimed is:

1. Apparatus for automatically injecting a liquid into a fluid system at a controlled pressure comprising a syringe containing said liquid and including a piston for discharging said liquid therefrom, an injector connected to said syringe for injecting said liquid into said system, a drive motor operatively connected to advance said piston so as to discharge liquid from said syringe, and means responsive to pressure variations of said discharged liquid above and below a predetermined pressure for automatically interrupting and resuming the advancement of said piston whereby said liquid is injected at a controlled pressure.

2. Apparatus for automatically injecting a liquid into a fiuid system at a controlled pressure comprising a syringe containing the liquid to be injected and including a piston for discharging said liquid therefrom, an injector connected to said syringe for injecting said liquid into said system, an electric motor operatively connected to advance said piston upon operation of said motor, a switch connected in series with said motor for energizing and deenergizing said motor, md means responsive to discharge pressure variations of said liquid above and below a predetermined pressure for automatically opening and closing said switch whereby said liquid is injected into said system at a controlled pressure.

3. Apparatus for automatically injecting a liquid into the lymphatic system of a patient at a controlled pressure comprising a syringe containing the liquid to be injected and including a piston for discharging said liquid therefrom, a hypodermic needle connected to said syringe for insertion into the lymphatic system, a drive motor operatively connected to advance said piston upon operation of said motor, a switch connected in series with said motor for energizing and deenergizing said motor, and means responsive to discharge pressure variations of said liquid above and below a predetermined value for automatically opening and closing said switch whereby said liquid is injected into the lymphatic system at a controlled pressure.

References Qited in the file of this patent UNITED STATES PATENTS 1,751,139 Feinstein Mar. 18, 1930 1,794,215 Titus Feb. 24, 1931 2,223,827 Kevelson et al. Dec. 3, 1940 2,690,178 Bickford Sept. 28, 1954 2,702,547 Glass Feb. 22, 1955 2,703,084 Tomlinson Mar. 1, 1955 2,782,682 Browning et al Feb. 26, 1957 3,033,195 Gilroy et al May 8, 1962 

1. APPARATUS FOR AUTOMATICALLY INJECTING A LIQUID INTO A FLUID SYSTEM AT A CONTROLLED PRESSURE COMPRISING A SYRINGE CONTAINING SAID LIQUID AND INCLUDING A PISTON FOR DISCHARGING SAID LIQUID THEREFROM, AN INJECTOR CONNECTED TO SAID SYRINGE FOR INJECTING SAID LIQUID INTO SAID SYSTEM, A DRIVE MOTOR OPERATIVELY CONNECTED TO ADVANCE SAID PISTON SO AS TO DISCHARGE LIQUID FROM SAID SYRINGE, AND MEANS RESPONSIVE TO PRESSURE VARIATIONS OF SAID DISCHARGED LIQUID ABOVE AND BELOW A PREDETERMINED PRESSURE FOR AUTOMATICALLY INTERRUPTING AND RESUMING THE ADVANCE OF SAID PISTON WHEREBY SAID LIQUID IS INJECTED AT A CONTROLLED PRESSURE. 